1. Field of the Invention
The present invention relates to an image input/output apparatus, an image processing apparatus, an image processing method, a data communication apparatus and a data communication method which perform a predetermined image process for image data.
2. Related Background Art
A digital multifunctional machine which includes various functions such as a scanner function, a printer function, a copying machine function, a network function and the like has been known, and in such the digital multifunctional machine, functional operations are generally controlled by an image input/output control apparatus called a controller.
In recent years, according as the digital multifunctional machine becomes sophisticated, an image input/output control apparatus capable of effectively processing a large amount of data is desired, and a controller for a multifunctional apparatus structured on a single semiconductor substrate as shown in Japanese Patent Application (Laid-Open) No. 11-45225 is proposed. Besides, a controller for a multifunctional apparatus structured so that plural image processing units are connected to a single shared bus represented by a PCI (peripheral component interconnect) bus is proposed.
However, if it tries to add or change a processing function when processing capability is insufficient, since the above controller of the multifunctional apparatus includes an image processing unit, a system control unit and the like on the single semiconductor substrate, there is a problem that such a structure can not be easily changed.
Further, even if the controller includes the PCI bus, such the controller has the structure that image data is sent in the shared bus. Therefore, even if the number of processing units increases to increase the processing capability, there is a problem that system performance is limited by the single shared bus.
In such a case, it is possible to provide a high bus control function so that the system performance is not limited. However, there is a problem that the number of structural parts increases, and thus the price of the apparatus becomes expensive as a whole.
Further, for example, in a case where a scanning operation and a printing operation are simultaneously performed, even if the apparatus includes plural image processing units, there is a problem that the processes concentrate on the one image processing unit and thus the competition for the image processing unit may occur.
Further, a technique to packet image data and then process a generated packet for improving efficiency of process, reducing memories, and the like is proposed. In general, when packet image data is transmitted, information representing the data length is written on the packet header, whereby the packet is transmitted among various units after the packet length was established.
However, in such a case where the packet image data is transmitted after the data was compressed, since the packet length is not established if the data compression does not end, it is necessary to transmit the packet image data after the compression ended. That is, a buffer for storing the packet image data before it is transmitted is necessary. Here, it is generally difficult to predict the data capacity after the data was compressed, and there is a possibility that the data capacity after the data compression becomes larger than the original data capacity. If so, since it is necessary to secure the capacity of the buffer to have sufficient room, a remarkably large capacity might become necessary when the maximum capacity of the image data included in the image data packet to be processed is large.